(a) Technical Field of the Invention
The present invention generally relates to devices for manufacturing corrugated paperboards, and more particularly to a device for exerting uniform pressure during the adhesion process of manufacturing double-faced corrugated paperboards.
(b) Description of the Prior Art
FIG. 1 is a schematic diagram showing a conventional manufacturing device for double-faced corrugated paperboards. As illustrated, adhesive is applied to the corrugated side of a single-faced corrugated paperboard 140 by a glue roll 130 which is driven by a wiper roll 132. Opposite to the glue roll 130, there is a rider roll 134 exerting pressure on the paperboard 140 so that adhesive could be applied uniformly. A liner 142 is then joined to the adhesive-applied corrugated side of the single-faced corrugated paperboard 140, thereby forming a double-sided corrugated paperboard. A rolling device containing a roll 112 and a belt 110 advances the paperboard 140 and the liner 142 by friction to the hot plates 120 to expedite their adhesion. A number of hold-down rolls 114 exert force on the paperboard 140 as it passes to enhance the adhesion effect.
The foregoing process has a number of disadvantages. First, there are only limited, linear, and separate contact areas between the hold-down rolls 114 and the paperboard 140, meaning that the paperboard 140 is not pressurized uniformly. In addition, the problem is worse if the surfaces of the hot plates 120 are not flat enough.